The proteasome (or macropain) (EC 126.96.36.199) [1,2,3,4,5,6,7] is a multicatalytic
proteinase complex that seems to be involved in an ATP/ubiquitin-dependent
nonlysosomal proteolytic pathway. The core of this 2.5 MDa enzyme complex is
formed by the 20S proteasome, a barrel-shaped protease of about 700 KDa that
associates with one or two 19S regulatory complexes. All archaea and
eukaryotes have a 20S proteasome as well as some actinobacteria , but most
bacteria have a simpler homologous structure heat shock locus v (HslV) or
The main difference between prokaryotic and eukaryotic proteasomes is one of
complexity. Prokaryotic 20S proteasomes contain mostly only to different but
related subunits, α and β (see <PDOC00668>), while eukaryotic
proteasomes contain seven paralogous α-type and seven paralogous β-type
subunits. Subunits that belong to the β-type group are proteins of from 190
to 290 amino acids that share a number of conserved sequence regions. The HslV
subunit has sequence similarity with the β-type subunits of the 20S
Some subunits that are known to belong to this family are listed below:
- Vertebrate subunits C5, β, delta, epsilon, theta (C10-II), LMP2/RING12,
C13 (LMP7/RING10), C7-I and MECL-1.
- Yeast PRE1, PRE2 (PRG1), PRE3, PRE4, PRS3, PUP1 and PUP3.
- Drosophila L(3)73AI.
- Fission yeast pts1.
- Thermoplasma acidophilum β-subunit. In this archaebacteria the
proteasome is composed of only two different subunits.
- Rhodococcus erythropolis 20S proteasome β subunit 1 (PrcB 1) and 2 (PrcB
- Escherichia coli ATP-dependent protease subunit HslV (EC=188.8.131.52).
The proteasome β-type subunit structure consists of a core of two
antiparallel β sheets that is flanked by α helices on both sides (see
As a signature pattern for proteasome B-type subunits we selected the best
conserved region, which is located in the N-terminal part of these proteins.
The pattern is specific for the 20S-subtype and does not detect the HslV-subtype. We also have developed a profile which covers the whole conserved
region of both subtypes.
PROSITE is copyright. It is produced by the SIB Swiss Institute
Bioinformatics. There are no restrictions on its use by non-profit
institutions as long as its content is in no way modified. Usage by and
for commercial entities requires a license agreement. For information
about the licensing scheme send an email to